Testing fixture for gear cutters



Aug. 14, 1934. s. H. EARL TESTING FIXTURE FOR GEAR CUTTERS 2 Sheets-Sheet 1 Filed Aug. 21, 1929 INVENTOR ZZQS ATTORNE 2 Sheets-Sheet 2 ari /7547i INVENTO Z Sckza yang? Agg. 14, 1934. s. H. EARL TESTING FIXTURE FOR GEAR CUTTERS Filed Aug. 21, 1929 h erence to face .IDI

Fatentecl Aug. i4, 1934 TESTING FIXTURE FOR GEAR CUTTERS Schuyler H. Earl, Rochester, N. Y., assignor-to Gleason Works, Rochester, -N. Y., a corporation .01" New York Application August 21, 1.929, Serial No. 387,536 3 Claims. (01. 33-472) The present invention relates to apparatus for testing the angles of the blades of face mill cutters such as are used in cutting spiral bevel and hypoid gears. The invention has particular refmill cutters having inserted blades.

The purpose of the present invention is to provide a simple, efficient and inexpensive device for testing the blade angles of a cutter so as to determine whether corresponding blades outside or inside, have corresponding pressure angles. The device has, also, been made sufliciently rigid and sturdy to permit stoning of the bottom of any of the slots of the cutter head to correct for any error in the pressure angle of a blade should it be found to have a other outside or inside blades.

A feature of the present invention is that it permits the same indicating device to be used to test both inside and outside blades of the cutter.

The principalobjects of the invention have already been mentioned. Other objects'will be apparent hereinafter from the specification and from the recital of the appended claims.

In the drawings:

v Figure 1 is a side elevation of a testing fixture constructed according to a preferred embodiment of the present invention, the cutter head being shown in section mounted thereon;

Figure 2 is a partial elevational View looking at rightangles to the view of Figure 1 and at the face of the cutterhead;

Figure 3 is a fragmentary sectional View Show-:

ing particularly the means for holding and clamping the cutter head carrier; and

Figure 4 is a view showing a detail of the means for adjusting the cutter head carrier angularly.

Face mill gear cutters have blades, the cutting portions of which project beyond the face ofv the cutter head in the general directionof the axis are inclined to the axis of the cutter soas to the gears to be cut.

'ent inclinations to the axis of the cutterdepending upon the spiral angle, dedendum angle, etc. of the gears to be cut as is well known in the,

art. The apparatus of the present invention per mits testing face mill gear cutters to determine whether or not the corresponding side cutting faces have all they same efieetive pressureangle.

In the drawings, indicates the base of the testing fixture. This base 10 has a plane horizon- 3 tal upper face 11 with a dove-tail guide portion pressure angle different from against rotation on its 'of the cutter. The side cutting faces of the blade 12 projecting therefrom. ,13, designates a slide. This slide has a plane bottom face with a recess therein conforming to the shape of the dovetailed guide 12. The slide 13 is mounted on the upper face of the hassle and is movable thereon for a purpose which will hereinafter be described.

Mounted on the slide 13 for pivotal adjustment thereon is a cutter head carrier 15. The cutter head carrier 15 pivots about the axis of the pivot pin 16 which is carried in suitable lugs or ears formed on the slide 13. The cutter head carrier isadapted to be adjustably secured to the piece or bracket 17, which is clearly shown in Figure 4, by means of a bolt 18 that is mounted in thecutter head carrier 15 and passes through the arcuate slot 19 formed in the member or bracket 1-7 and by means ofa nut (not shown) mounted on the bolt a'nd manipulated by the lever arm 20. The piece or bracket 1'7 is mounted on the pivot pin 16, an opening being provided at one end, as indicated At its other end, the piece or bracket 17 is threaded to receive a set-screw 23 which is adapted to engage a ledge 24 formed on the slide 13 to adjust the piece or bracket 17 itself about the axis of the pivot pin 16 thereby to secure a fine adjustment of the'cutter head carrier 15. h

'25 designates the head and 26 the blades of a face mill cutter of known construction. The blades 26 are adjustable radially of the axis of the cutter head bymeans of the usual shims 27 and wedges 28 and are secured to the cutter head by the bolts 29. The cutting portions of the blades project beyond the adjacent face of the cutter head in the general direction of the axis of the cutter head and the side faces of the blades are inclined to each other and to the axis of the cutter head in accordance with the pressure angle and number of the cutter.

Only four blades have been shown on the. cutterillustrated in the drawings, i; will be understood, however, that the'present apparatus is intended to test cutters of the standard number of blades or'of any desired number of blades. In the drawings, moreover, the cutter has been shown with alternate blades constructed to cut opposite side faces of the gear teeth. The apparatus of the present invention can be used, however, to test cutters having either or all outside cutting blades or to test cutters in which eachof the blades is'constucted so as to have both outsideand inside cutting edges.

at 21 for this purpose.

all inside The cutter to be tested is mounted on the cutidicarrier 15 roughly with reference to the member shown) which engage in the and with the nose 31 of the cutter head carrier entering the bore 32 of the cutter head 25 and centering the cutter head on the cutter head carrier. The cutter head is held on the cutter head carrier by a clamping plate 33 which is removably secured to the draw rod 35 by the nut 36.

The draw rod 35 slides in a bore in the cutter head carrier 15 and in the chamber 38 in thecutter head carrier which bore and which may, in fact, be considered an enlarged portion of the bore. A portion 3910f the draw-rod sliding within the chamber 38 is of increased diameter to correspond to the diameter of the chamber and between the inner end of this enlarged portion 39' and the inner end wall.

of the chamber there is interposed a coil-spring 40 that serves to hold the clamping plate 33 frictionally in engagement with the cutter head 25 to secure the cutter on the cutter head carrier. The draw-rod 35 can be drawn up to clamp the cutter head on the carrier against rotation by means of the nut 42 which is formed integral with the handle 43 and which threads on to the end of the draw bar. A washer 44 is interposed between this nut and the outer 38. A pin 41 on the enlarged portion 39 of the draw-rod that projects into'a slot 41 in the side wall of the chamber 38 serves to limit the movement of the draw-rod in both directions.

Mounted at one side of the base 10 for sliding adjustment in a direction parallel to the direction of movement of the slide 13 is a bracket 45. This bracket can be secured in any adjustedposition on the base 10 by means of T-boltsinot T-slots 46 formed in the side of the base. The bracket is formed with a slot or socket in which the vertically disposed post 4''? is slidably adjustable; The post can be adjusted by rotation of the shaft 48, this shaft carrying a pinion 49 which meshes with a rack 50 cut into one side of the post. The bracket 45 has a split-clamp portion engaging the post 47 which can be tightened by the bolt 51 to clamp the post in any adjusted position. This is a usual construction and. will be understood without further illustration.

Mounted on the post 4'? and clamped thereon by a split clamp and a screw 52 is an arm 53. This arm 53 serves to carry the movable contact member which is adapted to engage the blades of the cutter and the indicating means by which movement or" this contact member can be read. The contact member and indicating means may be of any usual or suitable form. In the drawings, the contact member is shown in the form of a pivoted lever 55 which has a contact tip at 56 that engages the blade and a nose at 5'? that serves to operate a plunger forming part of a standard form of indicating device designated as a whole at 59. A coil spring 60 serves to hold the nose 5? in engagement with the plunger of the indicating device.

To test a cutter,

ter head carrier 15 and the clamping plate 33 and nut 36 are then secured on the draw rod 35 to hold the cutter head on 40 is powerful enough against rotation for blade but will allow the carrier. The spring to hold the cutter head the operator to rotate the cutter head by hand without loosening up on the screw 36 to bring the successive blades into position tobe tested."

With the cutter head 25 mounted on the carrier 15, the operator first adjusts the cutter head communicates with v the 1 the cutter head carrier can end wall of the chamber it is first positioned on the cutthe purpose of testing a 17 to bring the side face of one of the blades into a horizontal plane. This will be indicated by a zero reading on the dial of the indicating device 59.

With the cutter blade so set, the blade is moved under the contact member. This is done by moving the slide 13 on the base 15. For convenience in. eiiecting this movement, the hand lever is provided. This is pivotally mounted on a stud 66 which is secured in the base 10 and ,is pivotally connected by a stud 67 with the slide 13. As the operator manipulates the lever 65, the slide 13 moves on the base 10 to move the blade being tested beneath the contact member.

Ifthe indicator reads zero for the full length of this movement, the side face of the cutting blade will lie in a horizontal plane. If the zero reading is not'obtained, the angular position of be changed by chang ing the rough adjustment of the cutter head carrier on the piece 17" andby thefine adjustment which can be secured'by manipulating the setscrew23. i I w When a zero reading has been obtained for the full length of the cutting face of one blade, the operator will rotate the cutter head to bring the next corresponding side blade into testing position. If a zero reading is not obtainedfor thewhole length of this new blade when the that thepressure angle of the side face of this blade is notthe same as the'pr'essure angle of the blade by which the instrumenthas been adjusted; To bring this second blade into position where it 'will'cutwith the same pressure angle as the first have to be removed fror'nthe-cutter head with its shim and wedge and the bottom of the slot in which the blade is secured will have-to be stoned until when the blade is reset in the cutter head its cutting pressure angle will be the same as'the cutting pressure angles of the other corresponding blades. The testing fixture is sturdy and rigid enough to permit the stoning operation to be effected on the fixture itself. So a reading will be taken on all corresponding blades and stoning will be effected where'necessary, until all corresponding blades have the same effective cutting pressure angle. For the stoningoperation, the cutter h'eadcarrier 15 can be clamped rigidlyagainst rotation by threading up on the nut 42. In the drawings, the contact member 55 and the indicating device 59 areshown in full lines in position for testing the inside blades. The outside cutting blades can be tested by moving the post 4'7 vertically and by moving the bracket 45 horizontally .on the base 10 to bring the contact'member 55 into the dotted line position shown in Figure 3 where it will be in operative relation with the outside cutting blades when the cuttingfaces oflthese blades are in a horizontal plane. An operation similarto that already descrlbed for the testing of the inside blades will be proceeded with in the testing of the outside blades. The cutter head carrier will be adjusted angularly until a zero'reading is obtained on the indicator for the full length of one of the outside cutting blades as that blade is moved beneath the indicator by'movement of the slide 13. As'ucceeding outside-blade will then be rotated inte position and its reading taken and so on. If a zero reading should not be obtained'on one of these succeeding outside blade, the "second blade will blades, that blade would be removed and the bottom of its slot stoned until it could be secured to the cutter head to have the same eifective cutting angle as the blade originally tested.

For convenience in setting the contact member, the arm 53 can be rotated angularly on the post 47 by loosening up on the clamping bolt 52 and a fine vertical adjustment can be obtained by manipulation of the set-screw which engages this arm 53.

To avoid too great a movement of the slide 13 back and forth during the testing of the blades, the adjustable stop-screws 72 and 73 are provided. These are secured in lugs 74 and 75, respectively, formed on a bracket 76 that is secured by screws 77 to the side of the slide 13 and they are adapted to engage one side or the other of a lug 78, that is formed integral with the base 10 and projects at one side therefrom, to limit the movement of the slide 13 under manipulation of the operator.

The fixture, as described, is designed specifically as a comparator to effective cutting pressure angle on all the blades of a cutter head. It will ever, that if desired a scale might be provided to permit setting the cutter head carrier 15 to the pressure angle desired on the blades to permit testing these blades exactly for this pressure angle.

The base 10 of the fixture may be mounted.

upon a bench or for convenience a stand may be provided, as shown in Figure 1 of the drawings. This stand is provided with a foot or pedestal 75 which is adapted to receive the post 76 that carries table 77 on which the base 10 of the fixture is secured by means post 76 can be adjusted vertically in the pedestal 75 to permit adjusting the testing fixture to a the pedestal.

It will be understood that instead of reciprocating the cutter to move the contact member member is reciprocated and the cutter carrier is held stationary.

In general it may be said that while the invention has been described in connection with a specific structure, it is to be understood that it is capable of various further modifications and that this application is intended to tions, uses, or embodiments Having thus described my invention, what I claim is:

1. In a device for testing the angles of the blades of a face mill gear cutter, a base, a slide permit securing the same be understood, howof the bolts 78. The Y 3 reciprocable on the base, a cutter carrier and a movable contact member, one of which is mounted on said slide and the other on said base, said cutter carrier being provided tatably supporting a cutter to be tested and being angularly adjustable on its support to permit adjusting a side face of one blade of the cutter so that it extends in parallelism to the direction of movement of the slide, an indicating member operatively connected with said contact member,

contact member into engagement with opposite side cutting faces of blades of the cutter to be tested.

2. In a device for testing the angles of the blades of a face mill gear cutter, a base, a slide reciprocontact, means for mounting the same on the base for movement resiliently in a direction transverse said slide, and

for positively clamping the cutter against rotation, means for adjusting the carrier angularly on inclination of the cutting edge relative to the direction of movement of the reciprocable support.

SCHUYLER H. EARL. 

